A density functional theoretical investigation of RhSin（n = 1-6） clusters

This paper computationally investigates the RhSin （n = 1 6） clusters by using a density functional approach. Geometry optimizations of the RhSin （n = 1 6） clusters are carried out at the B3LYP level employing LanL2DZ basis sets. It presents and discusses the equilibrium geometries of the RhSin （n = 1-6） clusters as well as the corresponding averaged binding energies, fragmentation energies, natural populations, magnetic properties, and the energy gaps between the highest occupied molecular orbital and the lowest unoccupied molecular orbital. Theoretical results show that the most stable RhSin（n = 1-6） isomers keep an analogous framework of the corresponding Sin＋1 clusters, the RhSi3 is the most stable cluster in RhSin （n = 1-6） isomers. Furthermore, the charges of the lowest-energy RhSin （n = 1-6） clusters transfer mainly from Si atom to Rh atom. Meanwhile, the magnetic moments of the RhSin（n = 1-6） arises from the 4d orbits of Rh atom. Finally, compared with the Sin＋1 cluster, the chemical stability RhSin clusters are universally improved.     

SimGen(m+n=9)团簇结构和电子性质的计算研究

硅锗团簇结构与电子性质的研究对于研发新型微电子材料具有重要意义. 将遗传算法和基于密度泛函理论的紧束缚方法相结合, 研究了Si_mGe_n(m+n=9)团簇的原子堆积结构和电子性质. 计算结果发现, Si_mGe_n(m+n=9) 团簇存在两种低能原子堆积稳定构型: 带小金字塔的五边形双锥堆积和带桥位Ge原子的四面体紧密堆积. 随着团簇内锗原子数目的逐渐增加, 两种堆积结构均出现明显的转变, 其中最低能量的几何结构由单侧带相邻双金字塔的五边形双锥结构转变为双侧带相邻单金字塔的五边形双锥结构. 随着原子堆积结构的变化, 团簇内原子电荷分布及电子最高占据轨道与电子最低未占据轨道的能隙随团簇内所含硅和锗元素组分的不同呈现出明显的差异.     

WnNim(n+m=8)团簇的极性和光谱性质的理论研究

采用密度泛函理论(DFT)中的B3LYP方法,在LANL2DZ基组水平上对WnNim(n+m=8)团簇的各种可能构型进行了几何参数全优化,得到了它们的基态构型;并对基态构型的偶极距、极化率、红外光谱和拉曼光谱性质进行了分析,结果表明:团簇WnNim(n+m=8)都具有极性,富W团簇非线性光学效应强,容易被外加场极化;振动频率主要分布在0-350 cm-1范围内,团簇W4Ni4因其振动方式的特殊性,红外光谱和拉曼光谱在频率421.971 cm-1处,都有明显强峰;团簇W5Ni3因其结构的高对称性在振动光谱中出现多处共振现象.     

Density functional study of AunCu (n=1-7) clusters

The possible stable geometrical configurations and the relative stabilities of the lowest-lying isomers of copper-doped gold clusters,Au n Cu (n=1-7),are investigated using the density functional theory.Several low-lying isomers are determined.The results indicate that the ground-state Au n Cu clusters have planar structures for n=1-7.The stability trend of the Au n Cu clusters (n=1-7),shows that odd-numbered Au n Cu clusters are more stable than the neighbouring even-numbered ones,thereby indicating the Au 5 Cu clusters are magic cluster with high chemical stability.     

First-principle studies of the geometries and electronic properties of Cum Sin (2≤m+n≤7)clusters

The equilibrium geometries and electronic properties of CumSin （2 ≤m ＋ n ≤ 7） clusters have been studied by using density functional theory at the B3LYP/6-311＋G （d） level. Our results indicate that the structure of CuSin （n 〈6） keeps the frame of the corresponding Sin cluster unchanged, while for CunSi clusters, the rectangular pyramid structure of Cu4Si is shown to be a building block in many structures of larger CunSi clusters. The growth patterns of CumSin clusters become more complicated as the number of Cu atoms increases. Both the binding energies and the fragmentation energies indicate that the Si-Si bond is stronger than the Cu-Si bond, and the latter is stronger than the Cu-Cu bond. Combining the fragmentation energies in the process CumSin →Cu＋Cum-l Sin and the second-order difference △2E（m） against the number of Cu atoms of CumSin, we conclude that CumSin clusters with even number of Cu atoms have higher stabilities than those with odd rn. According to frontier orbital analyses, there exists a mixed ionic and covalent bonding picture between Cu and Si atoms, and the Cud orbitals contribute little to the Cu-Si bonding. For a certain cluster size （m ＋ n = 3, 4, 5, 6, 7）, the energy gaps of the most stable CumSin clusters show odd-even oscillation with changing m, the clusters with odd m exhibit stronger chemical reactivity than those with even m.[第一段]     

Geometric,stable and electronic properties of Aun-2Y2（n=3-8） clusters

Employing first-principles methods,based on the density function theory,and using the LANL2DZ basis sets,the ground-state geometric,the stable and the electronic properties of Aun-2Y2 clusters are investigated in this paper.Meanwhile,the differences in property among pure gold clusters,pure yttrium clusters,gold clusters doped with one yttrium atom,and gold clusters doped with two yttrium atoms are studied.We find that when gold clusters are doped by two yttrium atoms,the odd-even oscillatory behaviours of Aun-1Y and Aun disappear.The properties of Aun-2Y2 clusters are close to those of pure yttrium clusters.     

Li修饰的C24团簇的储氢性能

利用密度泛函理论研究了Li原子修饰的C₂₄团簇的储氢性能. Li原子在C₂₄团簇表面的最佳结合位是五元环. Li原子与C₂₄团簇之间的作用强于Li原子之间的相互作用, 能阻止它们在团簇表面发生聚集. 当Li原子结合到C₂₄表面时, 它们向C原子转移电子后带正电荷. 当氢分子接近这些Li原子时, 在电场作用下发生极化, 通过静电相互作用吸附在Li原子周围. 在Li修饰的C₂₄复合物中, 每个Li原子能吸附两到三个氢分子, 平均吸附能处于0.08到0.13 eV/H₂范围内. C₂₄Li₆能吸附12个氢分子, 储氢密度达到6.8 wt%.     

Density functional theory study of MgnNi2 (n=1-6) clusters

The geometries of Mg_nNi₂ (n=1-6) clusters are studied by using the hybrid density functional theory (B3LYP) with LANL2DZ basis sets. For the ground-state structures of Mg_nNi₂ clusters, the stabilities and the electronic properties are investigated. The results show that the groundstate structures and symmetries of Mg clusters change greatly due to the Ni atoms. The average binding energies have a growing tendency while the energy gaps have a declining tendency. In addition, the ionization energies exhibit an odd-even oscillation feature. We also conclude that n=3, 5 are the magic numbers of the Mg_nNi₂ clusters. The Mg₃ Ni₂ and Mg₅Ni₂ clusters are more stable than neighbouring clusters, and the Mg₄Ni₂ cluster exhibits a higher chemical activity.     

B$lt;sub$gt;$lt;i$gt;n$lt;/i$gt;$lt;/sub$gt;Y($lt;i$gt;n$lt;/i$gt;=1–11)团簇的结构和电子性质

利用密度泛函理论TPSSh方法对B采用6-311+G(d), 对Y采用Lanl2dz相对论有效势基组, 研究了B_nY (n=1–11)团簇的平均结合能、二阶能量差分、最高分子占据轨道和最低空轨道之间的能级间隙、极化率和第一静态超极化率等物理化学性质. 结果表明, 随着尺寸的增大, B_nY (n=1–11)团簇的最低能量结构从平面逐步演变为立体结构. 随硼原子数n的增加, 团簇的平均结合能表明了较好的热力学稳定性, 有利于Y掺杂B团簇形成较大的块体材料.二阶能量差分表明基态B₃Y, B₅Y和B₇Y团簇较相邻团簇稳定. 能隙表明了基态B₃Y, B₅Y, B₇Y和B₉Y的化学稳定性较高. 综合说明B_nY (n=1–11)硼团簇中, 基态B₃Y, B₅Y和B₇Y具有较好的稳定性. 极化率表明基态B_nY团簇的电子结构随B原子的增加趋于紧凑, 第一静态超极化率表明基态B₅Y, B₄Y, B₃Y和B₆Y平面结构的团簇具有明显的非线性光学性质, 为寻找性能优异的非线性光学材料提供了一定的参考. 关键词： 密度泛函TPSSh方法 nY (n=1–')" href="#">B_nY (n=1– 11)团簇 几何结构 电子性质     

Density functional theory study on Ni-doped MgnNi (n=1-7) clusters

The possible geometrical and the electronic structures of small MgnNi(n = 1-7) clusters are optimised by the density functional theory with a LANL2DZ basis set.The binding energy,the energy gap,the electron affinity,the dissociation energy and the second difference in energy are calculated and discussed.The properties of Mg n Ni clusters are also discussed when the number of Mg atom increases.     

锂原子修饰B6团簇的储氢性能研究

利用密度泛函理论研究B₆和Li_mB₆ (m= 1–2)团簇的结构及其储氢性能. 结果表明, 氢分子在B₆团簇的三种可能结构中均发生解离吸附, Li原子在B₆团簇表面不发生团聚,每一个Li原子均吸附几个氢分子. 其中以两个Li原子修饰笼形B₆团簇吸附完整氢分子数最多,储氢质量分数为20.38%, 氢分子的平均吸附能为1.683 kcal/mol,表明了它在常温常压条件下作为储氢材料的可行性. 关键词： mB₆ (m=1-2)团簇')" href="#">Li_mB₆ (m=1-2)团簇 密度泛函理论(DFT) 吸附能 储氢性能     

The structural,electronic, and magnetic properties of SrFeOn（n=2 and 2.5）： a GGA＋U study

Using density-functional calculations within the generalized gradient approximation (GGA)+U framework,we investigate the structural,electronic,and magnetic properties of the ground states of SrFeOn (n = 2 and 2.5).The magnetism calculations show that the ground states of both SrFeO2 and SrFeO2.5 have G type antiferromagnetic ordering,with indirect band gaps of 0.89 and 0.79 eV,respectively.The electronic structure calculations demonstrate that Fe cations are in the high-spin state of (dz2 )2(dxz,dyz)2(dxy)1(dx2 y2 )1(S = 2),unlike the previous prediction of (dxz,dyz)3(dxy)1(dz2 )1(dx2 y2 )1(S = 2) for SrFeO2,and in the high-spin state of (dxy,dxz,dyz,dx2 y2 ,dz2 )5(S = 5/2) for SrFeO2.5.     

Density functional theory study of Mg_2Ni_n(n= 1–8) clusters

The density functional theory B3PW91 with LANL2DZ basis sets has been used to study the possible geometries of Mg2Nin(n = 1–8) clusters. For the lowest energy structures of the clusters, stabilities, electronic properties, and natural bond orbital(NBO) are calculated and discussed. The results show that the doped Mg atoms reduce the stabilities of pure Ni clusters. The Mg2Ni2, Mg2Ni4, and Mg2Ni6clusters are more stable than neighboring clusters. The system appears magic number characteristics. In addition, the hybridization phenomenon occurs, owing to the interaction of Mg and Ni. The result of charge transfer is that Ni atom is negative and the Mg atom is positive. We also conclude that the 3p and 4d orbitals of the Ni atom have an effect on the stabilities of the clusters.     

Density functional theory study of neutral AlS_n(n=2-9) clusters

This paper investigates the geometrical structures and relative stabilities of neutral AlS n(n = 2-9) using the density functional theory.Structural optimisation and frequency analysis are performed at the B3LYP/6-311G(d) level.The ground state structures of the AlS n show that the sulfur atoms prefer not only to evenly distribute on both sides of the aluminum atom but also to form stable structures in AlS n clusters.The structures of pure S n are fundamentally changed due to the doping of the Al atom.The fragmentation energies and the second-order energy differences are calculated and discussed.Among neutral AlS n(n = 2-9) clusters,AlS 4 and AlS 6 are the most stable.     

钇覆盖Si@Al12团簇的贮氢性能

利用密度泛函理论系统地研究了Y_mSi@Al₁₂ (m=1—3)团簇及其贮氢性质. 结果表明, 在所研究的尺度范围内, 钇原子未在Si@Al₁₂团簇上团聚; 每个钇原子按18电子规则吸附氢分子, 其中Y₃Si@Al₁₂团簇可以吸附16个完整氢分子, 贮氢质量分数为5.0 %, 平均吸附能处于0.324—0.527 eV之间, 较为理想的吸附能说明在室温条件下吸氢和脱氢是可行的.     

TiGen-(n=7~12)团簇的光电子能谱及密度泛函理论研究

利用光电子能谱及密度泛函理论计算对TiGe_n^-(n=7~12)团簇的几何结构及电子特性等进行了系统研究. 对于TiGe_n^-负离子及中性TiGe_n,在n=8时出现了钛原子半内嵌的船型结构;在n=9~11时,新增的锗原子加盖到这种船型结构上,逐步形成钛原子完全内嵌的结构. TiGe₁₂^- 团簇具有一种钛原子内嵌的变形六棱柱结构. 自然布居分析结果显示,对于n=8~12的TiGe_n^-/0 团簇,随着内嵌结构的形成,有电子从锗原子转移到钛原子,说明其电荷转移方式与结构演变密切相关.     

PdnPbm(n+m≤5)混合团簇的结构与光谱性质

在相对论有效原子实势(RECP)近似下，用密度泛函中的B3LYP/LANL2DZ方法，对纯Pb_n(n=2—5)团簇、Pd_nPb_m(n+m≤5)混合团簇的各种可能几何构型进行全优化计算，得到它们的基态结构和光谱性质；从结构和振动光谱两个方面分析了其形成规律；最后计算了团簇的能级分布和最高占据轨道(HOMO)与最低空轨道(LUMO)之间的能级间隙(HLG)，分析了团簇的化学活性. 关键词： 团簇 有效原子实势 密度泛函     

NO在Yn(n=1–12)团簇表面的解离性吸附

采用基于密度泛函理论中的广义梯度近似,在考虑自旋多重度的情况下,对Y_nNO（n=1–12）团簇进行了构型优化,以及稳定性和成键特性分析,结果表明：n=5,7,8,10时,NO吸附使相应的Y_n团簇基态结构发生了明显变化,吸附后,所有尺寸中的N–O键长明显伸长,振动频率减弱,表明NO在Y_n团簇表面发生的是解离性吸附,N–Y,O–Y键的共同作用使Y_nNO团簇具有很大的吸附能;特别是n=3,5,8时,N–O键断裂,吸附能值分别为9.92,9.24,9.82 eV. Y_nNO和Y_n 的二阶能量差分变化趋势表明,NO 吸附对Y_n团簇稳定性和成键特性均产生较大影响. N,O原子sp³轨道杂化时孤对电子的出现导致N–O键断裂,增强了N–Y和O–Y间的成键能力,使Y₃NO,Y₅NO,Y₈NO团簇表现出了很好的稳定性. 关键词： 团簇 NO吸附 基态结构 稳定性     

Structures and electronic properties of Mo2nNn（n=1-5）:a density functional study

The lowest-energy structures and the electronic properties of Mo2nNn(n=1-5) clusters have been studied by using the density functional theory(DFT) simulating package DMol 3 in the generalized gradient approximation(GGA).The resulting equilibrium geometries show that the lowest-energy structures are dominated by central cores which correspond to the ground states of Mo n(n = 2,4,6,8,10) clusters and nitrogen atoms which surround these cores.The average binding energy,the adiabatic electron affinity(AEA),the vertical electron affinity(VEA),the adiabatic ionization potential(AIP) and the vertical ionization potential(VIP) of Mo2nNn(n=1-5) clusters have been estimated.The HOMO-LUMO gaps reveal that the clusters have strong chemical activities.An analysis of Mulliken charge distribution shows that charge-transfer moves from Mo atoms to N atoms and increases with cluster size.     

(HMgN3)n(n=1–5)团簇结构与性质的密度泛函理论研究

利用密度泛函理论在B3LYP/6-311G^*水平上对叠氮化合物(HMgN₃)_n(n=1–5)团簇各种可能构型进行了几何优化,预测了各团簇的最稳定结构. 并对最稳定结构的成键特性、电荷分布、振动特性及稳定性进行理论研究. 结果表明:HMgN₃团簇最稳定结构为直线型;(HMgN₃)_n(n=2,5)团簇最稳定结构为叠氮基中N原子和金属原子相连构成Mg–N–Mg结构;(HMgN₃)_n(n=3,4)团簇最稳定结构为叠氮基与Mg原子相互链接形成的环状结构. 团簇最稳定结构中金属Mg原子均显示正电性,H原子均显示负电性,叠氮基中间的N原子显示正电性、两端的N原子显示负电性,且与Mg原子直接作用的N原子负电性更强. Mg–N键和Mg–H键为典型的离子键,叠氮基内N原子之间是共价键. 团簇最稳定结构的红外光谱分为三部分,其最强振动峰均位于2258–2347 cm^-1,振动模式为叠氮基中N–N键的反对称伸缩振动. 叠氮基在团簇和晶体中结构不变,始终以直线型存在. 稳定性分析显示,(HMgN₃)₃团簇相对于其他团簇更为稳定. 关键词： 3)_n(n=1–5)团簇')" href="#">(HMgN₃)_n(n=1–5)团簇 叠氮基 密度泛函理论 结构与性质